Cyclic Atomic Layer Deposition of Hafnium Aluminate Thin Films Using Tetrakis(diethylamido)hafnium, Trimethyl Aluminum, and Water

Hafnium aluminate thin films were deposited at 225 °C by cyclic atomic layer deposition (ALD) of hafnia and alumina with Hf(N(C2H5)2)4 (tetrakis(diethylamido)hafnium: TDEAH), Al(CH3)3 (trimethyl aluminum: TMA), and H2O. The multi‐component thin films were formed by switching between the alumina and hafnia deposition cycles, and the chemical composition of the film was controlled by adjusting the number of cycles of each oxide. The surface of the film was very smooth and the formation of an interfacial layer was suppressed. The crystallization temperature of the film became higher as the Al incorporation in the film was increased. The hafnium aluminate thin film with the composition Hf0.68Al0.32Ox showed a dielectric constant of 13.94 and leakage current of 4.3 × 10–7 A cm–2 at 1 MV cm–1. At this composition, the formation of an interfacial layer was minimal after rapid thermal annealing (RTA).